Seed dormancy regulated by genotype and environment in Hairy vetch (Vicia villosa Roth)

Authors: Kissing Kucek, Lisa; Azevedo, Mark; EAGEN, SARAH SEEHAVER - North Carolina State University; EHLKE, NANCY - University Of Minnesota; Hayes, Ryan; Mirsky, Steven; REBERG-HORTON, C - North Carolina State University; RYAN, MATT - Cornell University; WAYMAN, SANDRA - Cornell University; WIERING, NICHOLAS - University Of Minnesota; Riday, Heathcliffe

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2020
Publication Date: 11/13/2021
Publication URL: https://handle.nal.usda.gov/10113/7188056
Citation: Kucek, L.K., Azevedo, M.D., Eagen, S., Ehlke, N., Hayes, R.J., Mirsky, S.B., Reberg-Horton, C., Ryan, M.R., Wayman, S., Wiering, N.P., Riday, H. 2021. Seed dormancy regulated by genotype and environment in Hairy vetch (Vicia villosa Roth). Agronomy Journal. 10(11). Article 1804. https://doi.org/10.3390/agronomy10111804.
DOI: https://doi.org/10.3390/agronomy10111804

Interpretive Summary: Some crops produce seed with a hard coating ("hard seed") that delays the uptake of water, germination, and seedling growth and this can make it difficult for farmers to get crops properly established for production. Moreover, hard seed that eventually germinates can become a weed in subsequent crops grown on a farm. Hairy vetch is an example of a useful crop for animal feed and soil conservation, yet it has a high proportion of hard seed. We grew 1693 plants of hairy vetch in 18 locations in the USA and found that hard seed is a moderately inherited trait. Consequently, breeding programs should be able to develop varieties that do not produce hard seed. We also demonstrated that weather conditions where plants are grown for seed production influence the amount of hard seed produced. Environments that have lower humidity during seed drying will produce more hard seed. Ultimately the development and sale of new hairy vetch varieties without hard seed would help more farmers grow this useful crop.

Technical Abstract: Seed dormancy complicates agricultural use of many legume species. Understanding the genetic and environmental drivers of seed dormancy is necessary for advancing crop improvement for legumes, such as Vicia villosa. We quantified the magnitude of genetic and environmental effects on physical dormancy among 1693 maternal V. villosa plants from 18 diverse environments. Furthermore, we explored the relationship between physical dormancy and environmental conditions during seed development. Additive genetic variance accounted for 39.86% of variance, while growing environment explained 31.11% of variance in physical dormancy. Maternal lines showed complete variance in physical dormancy, with 39 lines exhibiting 100% hard seed, while 55 showed no physical dormancy. Distributions of physical dormancy varied strongly among seed production environments, with some site-years strongly skewed toward physically dormant seed, while other site-years exhibiting little dormant seed. Mean relative humidity during seed development was most associated with physical dormancy. Mean shortwave radiation, mean precipitation, cumulative hours below 50% relative humidity, and mean temperature also indicated influence. Weather variables calculated from fixed time windows prior to seed harvest were less predictive than the relative seed drying windows calculated for each maternal line. With moderate heritability, breeding programs can select against physical dormancy and improve V. villosa for agricultural use. Research concerning physical dormancy should account for large environmental effects, which are dominated by relative humidity during seed drying. Within an environment, genotypes that vary in maturity timing will experience different weather conditions and exhibit differential physical dormancy.